Speed indicating device



Feah MCHENRY SPEED INDICATING DEVICE Filed June 19, 1946 INVENTOR LOREN C. MC HENRY ATTORNEY Patented Feb. 22, 1949 UNITED STATES FATENT OFFICE SPEED INDICATIN G DEVICE Loren C. Mcl-ienry, River-mines, Mo. Application June 19, 1946, Serial No. 677,699

2 Claims. 1

This invention relates to a speed indicating device, and more particularly to a device of a character which will give a signal when a machine supervised by the device falls below a predetermined normal speed.

An object of the invention is to provide a device which is simple in construction, economical to manufacture, efiicient in operation, and as free as possible from operating and maintenance dimculties.

A further object of the invention is to produce such a device which will have the smallest number of moving parts.

Other objects Will be apparent from the following detail description, taken in connection with the accompanying drawings.

Fig. 1 is a diagram showing a preferred embodiment of my invention; and

Fig. 2 is a diagrammatic View showing a modification.

In accordance with this invention a pulsator mechanically connected to and operating in synchronism with a machine is arranged to make and break an electric circuit in which there is a relay controlling a signal circuit. A condenser is connected in the first mentioned circuit in parallel with the relay and is so proportioned as to keep the relay energized when the pulsator and therefore the machine is operating at normal speed but permitting the relay to become when the speed drops below normal.

In the preferred embodiment the pulsator is shown in the form of a commutator I' which is driven by a shaft 2. This shaft is mechanically connected to an appropriate rotating shaft of the machine to be supervised. The shaft 2 may in fact be integral with or an elongation of such a machine shaft. For example, the shaft may be the tail puley shaft of a belt conveyor.

The commutator I has a plurality of electrical conductive segments 3 equi-spaced about the periphery of the commutator and electrically connected to a slip ring 4. The commutator is swept by a pair of brushes 5 and "6, so arranged with reference to the spacing of the segments 3 that one of them will be in contact with a segment 3 while the other is on a non-conductive portion of the commutator.

The system is fed by a circuit which includes the leads I and 3. The lead I, as specificially shown in the diagram, is connected to a brush 9 in contact with the slip ring 4. The lead 8 has branches I and II leading respectively to relays I2 and I3, which are connected respectively to the brushes and B by the lines I4 and I5.

deenergized Condensers It and ii are connected in parallel respectively with the relays I2 and I3, and have such a capacity with respect to the inductiveness the coils in their relays that they will keep the relays energized while the commutator I is moving at a normal rate of speed, but will permit the relays to become deenergized if the speed drops below a predetermined normal.

It will now be understood that a circuit, or circuits, can be controlled by the relays so that they will cause a signal to be given when the relays deenergized, as they will be when the speed drops below normal. One such signalling circuit 55 is illustrated as including a lamp I9 and is controlled in series by the relays l2 and I3. That is to the circuit I8 includes a contact of the relay I2 and. a contact 2| of the relay I3. These contacts are so arranged on their relays that they will be closed when the relays are energized. Therefore, when the machine to be supervised and the commutator I is rotating at normal speed both contacts 20 and M will be closed giving a steady light in the lamp I9. If either relay 52 or it becomes deenergized the circuit i8 will be broken momentarily causing the light it to flicker.

A second signalling circuit 22 is shown asfeeding in parallel a lamp 23 and a horn 24. This circuit 22 by branches 22a and 22b is arranged to be closed when either relay I2 or I3 is collapsed. The branch 22a connects through a contact 25 of he relay [2, and the branch 22bconnects through a contact 26 of the relay i 3.

It may now be further understood that upon a sub-normal speed one or both the contacts 25 and will be closed, due to the collapse of the respective relays I2 and 53, thereby closing the'circuit 22 to give a visible signal through the lamp 23 or an audible signal through the horn 24. It will be understood that either the visible signal, the lamp or the audible signal, the horn 24, may

or both may be employed-if desired.

For convenience a .vitch 2'! is employed to control the horn 24. Thus, if a signal has been received from the horn 24 and is understood the switch 21 may be opened to prevent noise and confusion. Furthermore the switch 2'! may be allowed to remain open upon starting the superimposed machine until the machine is brought up to normal speed.

A holding relay 28 may be employed in the circuit 22 and supplied by a self-locking circuit 29 closed automatically by a contact 30 of the relay 2%. Thus when either the relays I2 and I3 are momentarily deenergized to close the contacts '25 and 26, the relay 28 will be energized closing its contact 30, thereby causing a continuous flow of current in the circuit 22. A switch 3| in the holding circuit 29 can be used to control that circuit. It will be obvious that the use of the holding relay 28 and its self-locking circuit serves to give a continuous signal through the lamp 2% or the horn 24, whenever the speed drops below normal even if momentarily. It will be seen, however, that the signals will be efiective without the use of such holding relay but the signals will be intermittent rather than continuous.

An auxiliary circuit 32 may be arranged to be controlled by the relay 28 through a contact 33 for any purpose desired, such as for motor control.

As illustrated in the diagram a switch 34 may be used to control the supply circuit through the leads 1 and 8, so that the device may be electrical- 1y disconnected when not in use. Any convenient source of electrical supply may be employed and it has been found that the usual 110 volt cycle A. C. current may be satisfactory, as well as a direct current of any common voltage.

It will be apparent that the device is operative with only one brush, ,5 or 6, to produce a limited result. Two brushes are employed, however, to avoid a false signal when the commutator is at rest. Thus, if only one brush 5 were employed and the commutator were to stop suddenly in the position shown in the drawing, the relay l 2 would be energized and no correct signal would be given.

An alternate form of pulsator is shown in Fig. 2. In this embodiment a reciprocating member 40 is employed, having spaced segments Al and 42 connected in common to a conductor 43 which is wiped by a brush 9, similarly as the brush 9 makes contact with the slip ring 4 on the commutator l. The brushes 5 and 6 make contact with the segments s1 and c2, and comparable to the contact made by the brushes 5 and 6 in the preceding embodiment with the segments 3 on the commutator. A sliding member 40 is connected by a pitman 44 to a crank wheel 95 connected to the shaft 2.

It will be apparent from the foregoing description that the invention accomplishes its objects. A device has been supplied which will be efficient, and which is simple in construction and economical to manufacture. Few moving parts are employed. The device is largely electrical and employs inexpensive standard electrical parts, such as relays and condensers. These parts, and all the parts of the device are such as to have a long life and to be relatively free from trouble during operation. In case of repair, such repair entails merely the substitution of inexpensive new parts for those which have become worn or ineffective.

Various changes may be made in the details of construction, within the scope of the appended claims, without departing from the spirit of this invention.

It has already been pointed out that several signal circuits are employed, and it will be obvious that all of these need not be employed.

4 While a preferred method of applying the inveri tion has been illustrated and described, parts of this invention may be used to advantage without the whole, and additions and improvements may be made while retaining the fruits of the invention.

I claim:

1. Means indicating subnormal speed of a machine comprising a movable device having a plurality of electrical contact segments thereon mechanically connected and driven in synchronism with said machine, brushes positioned to alternately make and break contact with said segments as said device is moved, circuits connected to said brushes respectively, and controlled by said segments, relays connected in and energized by said circuits, condensers connected in the circuits, respectively, in parallel with said relays and proportioned to keep said relays energized when said machine is moving at normal speed but permitting said relays to become deenergized when said speed drops below normal, a circuit controlled by the relays, and a signaling device controlled by said circuit.

2. Means for indicating subnormal speed of a machine comprising a commutator having equispaced contact segments mechanically connected and driven in synchronism with a machine to be controlled, a slip ring electrically connected to the contact segments, brushes positioned to alternately make and break contact with said segments as said commutator is rotated, circuits connected to said brushes respectively, and controlled by said circuits, relays connected in and energized by said circuits, condensers connected in the circuits respectively in parallel with the relays and proportioned to keep the relays energized when said commutator is being rotated at normal speed but permitting them to become deenergized when said speed drops below normal, a signal circuit parallel controlled by said relays to close the circuit when the relay-s are deenergized, a warning device controlled by said circuit, and a holding relay, with a self-locking circuit, in and for said signal circuit arranged whereby a constant signal is given by said warning device after the signal circuit has been once closed by either of said first mentioned relays.

LOREN C. MCHENRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,571,969 Needham Feb. 9, 1926 2,008,912 l-Iudd July 23, 1935 2,130,453 Bone Sept. 20, 1938 2,333,210 Stern Nov. 2, 1943 2,337,132 Shaw Dec. 21, 1943 2,3e9,182 Lesnick May 16, 1944 FOREIGN PATENTS Number Country Date 572,018 Germany Mar. 9, 1933 

